Traditional vehicle braking systems employ a fluid-filled master cylinder and one or more brakes with brake cylinders. Fluid lines connect the master cylinder to the brake cylinders. When a driver presses on the brake pedal, a piston in the master cylinder forces brake fluid through the fluid lines to the brake cylinders, thereby causing the brakes to provide braking force against a disc or drum.
Many known vehicles also include an anti-lock brake system (ABS) that operates to reduce pressure in the brake cylinders if the wheels of the vehicle lock up and/or otherwise cease rotating. In such known systems, a valve is disposed in the fluid line between the master cylinder and the brake cylinder that closes the fluid connection between the master cylinder and brake cylinder. Then, a solenoid is activated to relieve pressure from the brake cylinder. Once the pressure is relieved, a separate pump is used to reapply pressure to the brake cylinder. The solenoid and the pump are used to alternately apply pressure and relieve pressure at a high frequency, which enables the brake to slow the vehicle without locking the wheel.